Solve for X using the matrices below.

Question

2A + 4B = −2X

A = 8 -5 and B = 0 7

1 0 2 0

9 -2 -2 -1

X = _____ _____

_____ _____

_____ _____

Answer 1

A = 8 -5 and B = 0 7

1 0 2 0

9 -2 -2 -1

find 2A + 4B = 2X

2A = 16 -10

2 0

18 -4

4B = 0 28

8 0

-8 -4

Therefore for 2A + 4B, just add the corresponding elements in 2 matrices:

2A + 4B = 16+0 -10+28

2+8 0+0

18-8 -4-4

= 16 18 = 2X

10 0

10 -8

To get the value of X is to divide every element 2A+4B by 2:

X = 16/2 18/2

10/2 0/2

10/2 -8/2

X = 8 9

5 0

5 -4